KR101776476B1

KR101776476B1 - X-ray ionizer

Info

Publication number: KR101776476B1
Application number: KR1020160034625A
Authority: KR
Inventors: 이동근
Original assignee: 이동근
Priority date: 2016-03-23
Filing date: 2016-03-23
Publication date: 2017-09-07

Abstract

An X-ray ionizer according to the present invention is an X-ray ionizer for discharging X-rays partially ionizing the atmosphere to remove static electricity of an electrified object. The X-ray ionizer includes an X-ray generating unit for generating the X-rays, a power unit for supplying power to the X-ray generating unit, and a control unit for controlling the operation of the power unit. A cathode of the X-ray generating unit includes carbon nanotubes, the power unit and the control unit are housed in at least one electromagnetic wave shield case, and the X-ray generating unit and the power unit are connected by a cable so as to be installed to be separated from each other.

Description

X-ray ionizer

The present invention relates to an x-ray ionizer, and more particularly, to an x-ray ionizer for inducing partial dissociation of the atmosphere by x-rays in order to reduce defects due to generation of static electricity in a manufacturing line of a semiconductor or a display device.

In the manufacturing process of semiconductors and display devices, static electricity negatively affects the yield of production through destruction of the insulating film of the device or adsorption of fine particles. Therefore, a static electricity removing device for suppressing the generation of static electricity is widely used in a semiconductor or display device manufacturing line.

Electrostatic eliminators include X-ray ionizers using x-ray emission, ion bar using corona discharge, and ion blowers. Among them, the ion bar and the ion blower have a problem of causing secondary contamination such as generation of fine particles in the discharge needle during the generation of ions. However, the X-ray ionizer ionizes the atmosphere by using the X-rays generated through the window, so that the chemical reaction is suppressed at the electrode surface like the corona discharge, so that there is no problem of contamination by the fine particles.

A prior art document relating to X-ray ionizers is Korean Patent Publication 2006-0014925. This prior art document discloses a tungsten filament and a nickel focusing tube coupled to a nickel electrode stem (2-9) by a spot welded joint, and a Be window and a Be window support coated with a target, Ray ionizer with an X-ray tube structure assembled into a structure. However, since the x-ray ionizer disclosed in the above-mentioned prior art uses a tungsten filament as an electron emitting source, the lifetime of the filament is shortened due to high temperature deterioration. Another prior art document is Korean Patent No. 0680760. The above-mentioned prior art discloses an X-ray ionizer capable of adjusting an X-ray emission direction by connecting an X-ray generator and a control unit with a flexible tube. However, since the X-ray ionizer disclosed in the above prior art uses tungsten as the electron emitting source, when the length of the flexible tube becomes long, a voltage drop occurs due to the electrical resistance and the heating temperature of tungsten becomes low. It can not be extended.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problem of a voltage drop due to the length of a connection cable by applying a cathode that emits electrons by field emission of carbon nanotubes and to store the power unit and the control unit in a single electromagnetic shielding housing Ray ionizer capable of protecting the power unit or the control unit from electromagnetic noise and improving the reduction of the X-rays due to deterioration of the carbon nanotubes.

In order to achieve the above object, the present invention provides an X-ray ionizer for discharging X-rays partially ionizing the atmosphere to remove static electricity of an electrified object, A power unit for supplying power to the X-ray generating unit, and a control unit for controlling operation of the power unit, wherein the cathode of the X-ray generating unit includes carbon nanotubes, and the power unit and the control unit are one And the X-ray generator and the power unit are connected by a cable so that they can be installed to be spaced apart from each other.

According to an embodiment of the present invention, the carbon nanotube may be grown directly on the metal substrate by chemical vapor deposition.

According to another embodiment of the present invention, the length of the cable is preferably 1 to 10 m.

The x-ray ionizer of the present invention has the following effects.

1. Since the X-ray generator of the present invention is made of carbon nanotubes that emit electrons by field emission, the X-ray generator does not need a power supply for heating the cathode, and thus the length of the cable connecting the X- Even when the length is sufficiently long, there is no reduction in electron emission due to the voltage drop. As a result, the length of the connecting cable between the x-ray generating unit and the power unit can be extended to 10 m or more, thereby improving the ease of installation of the x-ray ionizer.

2. The control unit and the power unit are housed together in one electromagnetic shielding case, and the distance between the case and the X-ray generating unit can be extended sufficiently long so that the control unit and the power unit can be separated from the X- As a result, it is possible to protect the control unit and the power unit from the electromagnetic noise caused by the X-ray.

3. The carbon nanotubes applied to the cathode of the X-ray generator are directly grown on the metal substrate constituting the cathode by chemical vapor deposition, so that the direction of arrangement of the carbon nanotubes can be guided toward the target material, High durability.

4. Since a step is formed on the surface of the cathode in the direction of the target material, electron emission is relatively increased in the carbon nanotube in a region where the distance from the target material is relatively relatively, and the deterioration of the carbon nanotube in the electron emission process is progressively So that changes in x-ray emission within operating lifetime can be minimized.

FIG. 1 shows the configuration of an X-ray generator, a power unit, and a control unit of an X-ray ionizer according to the present invention.
2 shows an X-ray generator of an X-ray ionizer according to an embodiment of the present invention.
FIG. 3 shows a power unit applied to an X-ray generator applied to an X-ray ionizer of the present invention.
4 illustrates a cathode structure of an x-ray ionizer according to an embodiment of the present invention.
FIG. 5 is a view for explaining a difference in electric field for each region when a step is formed on the surface of the cathode.
Figure 6 illustrates a cathode structure having a step that can be applied to an x-ray ionizer of the present invention.
FIG. 7 is a view for explaining whether or not the power section of the conventional X-ray ionizer of the present invention and the X-ray ionizer of the present invention are exposed to an X-ray.

The X-ray ionizer of the present invention is an X-ray ionizer that emits X-rays partially ionizing the atmosphere to remove static electricity of an electrified object. The X-ray ionizer includes an X-ray generator for generating X- A power unit for supplying power to the X-ray generating unit, and a control unit for controlling operation of the power unit, wherein the cathode of the X-ray generating unit includes carbon nanotubes, And the X-ray generating unit and the power unit are connected by a cable so as to be installed apart from each other.

The x-ray ionizer of the present invention has two characteristics.

First, the electron emission cathode of the x-ray generator is formed of carbon nanotubes, and the x-ray generator and the power unit are connected by a cable having a predetermined length. When the control unit and the power unit can be spatially separated from the x-ray generating unit, the volume of the x-ray generating unit can be reduced and the x-ray generating unit can be easily installed at a desired position in the space where the static eliminating operation is performed. Since the power unit is spatially separated, noise generated by the generated X-ray and manufacturing equipment can be prevented from entering the control unit or the power unit, thereby preventing malfunction. The reason why the x-ray generator and the power section can be connected with a sufficiently long cable, for example, 1 to 10 m in length, is that carbon nanotubes are used as electron emission emitters. When a tungsten filament emitting thermoelectrons is used as an electron emitting source, a separate power must be supplied for heating tungsten. However, if the length of the connection between the power unit and the X-ray generating unit becomes longer, the electrical resistance of the connecting cable becomes larger, The heating temperature of tungsten may be lowered. However, in the X-ray ionizer of the present invention, since the field emission electrons are used instead of the thermoelectrons, the above problems do not occur. The above-described configuration solves the problem of replacing the X-ray generator and the power unit at the same time when a failure occurs in the X-ray generator in the conventional X-ray ionizer in which the X-ray generator and the power unit are integrally formed, It also has an advantage.

The second is a step formed on the metal surface constituting the cathode of the X-ray generating part. The step formed in the cathode generating portion has an effect that the distance between the carbon nanotubes in the specific region and the target substance is larger than that in the other regions. The amount of electron emission in the field emission depends on the intensity of the electric field of the tip of the carbon nanotube, and the electron emission is more likely to occur in the carbon nanotube in a specific region due to the step formed in the cathode. When the end of the carbon nanotubes deteriorates, the length of the carbon nanotubes is shortened. In the X-ray ionizer of the present invention, since deterioration of the carbon nanotubes progresses step by step, the degree of change of the total electron emission amount can be minimized have.

An X-ray ionizer of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an X-ray generator, a power unit, and a control unit of an X-ray ionizer according to the present invention. 1, an X-ray ionizer 100 includes an X-ray generator 10, a power unit 20, and a control unit 30. The X-ray generator 10 and the power unit 20 include a cable 40). The power unit is a high voltage generating unit for emitting and accelerating electrons from the cathode of the X-ray generating unit toward the target material, and the control unit controls the operation of the power unit . The cable 40 functions as a wire for applying a high voltage generated in the power unit to the cathode of the X-ray generator and the target material.

2 shows an X-ray generator of an X-ray ionizer according to an embodiment of the present invention. 2, the x-ray generator includes a cathode 11, a target material 12, a window 13, and a sealing portion 14. The cathode (11) and the target material (12) are spaced apart from each other and opposed to each other. The cathode 11 has a structure in which carbon nanotubes 15 are formed on a metal substrate having a surface facing the target material 12. Since the carbon nanotubes grow directly on the metal substrate, they are oriented in the direction of the target material. The target material 12 may be made of a metal such as molybdenum, tungsten, or the like, and may be formed as a coating film on a window surface made of bell-lie. The window 13 has a function of transmitting X-rays generated from a target material to the outside and emitting the X-rays, and may be made of a material such as beryllium. The sealing part 14 is a part for holding a space in which a cathode, a target material or the like is installed in a vacuum, and may be made of ceramics or the like, and a joint part with the window can be sealed by using brazing welding or the like.

FIG. 3 shows a power unit applied to an X-ray generator applied to an X-ray ionizer of the present invention. Referring to FIG. 3, a negative voltage and a positive voltage are applied to the cathode 11 and the target material 12 or window, respectively, in the X-ray generator applied to the X-ray ionizer of the present invention. When an electric field is formed between the cathode 11 and the target material 12, electrons are emitted from the carbon nanotubes (not shown) formed on the surface of the cathode 11, and the emitted electrons are accelerated along the electric field to collide with the target material The X-rays are generated and the generated X-rays are emitted to the outside through the window.

4 illustrates a cathode structure of an x-ray ionizer according to an embodiment of the present invention. Referring to FIG. 4 (a), the cathode 11 applied to the X-ray ionizer of the present invention is formed with a step on the surface of a metal substrate of a disc shape, and a power connection terminal is formed on one side of the cathode. Although the metal substrate is shown in the form of a disk in the drawing, the metal substrate forming the cathode may have various shapes such as a circle, a square, and the like. 4 (B) shows a cross section of the cathode. The surface of the cathode includes a first horizontal plane 11a, a slope plane 11b and a second horizontal plane 11c. The first horizontal surface 11a constitutes a depression, the second horizontal surface 11c constitutes a protrusion, and the inclined surface 11b forms a connecting surface along a step between the first horizontal surface and the second horizontal surface. Carbon nanotubes are formed on the first horizontal surface 11a, the inclined surface 11b, and the second horizontal surface 11c. Since the carbon nanotubes are formed in such a manner that they are grown directly on the metal substrate, the ends of the carbon nanotubes as a whole can be arranged in the direction of the target material.

FIG. 5 is a view for explaining a difference in electric field for each region when a step is formed on the surface of the cathode. Referring to FIG. 5, the first horizontal surface 11a and the second horizontal surface 11c formed on the cathode surface have distances L2, L1 from the target material, respectively. When a predetermined voltage is applied to the cathode 11 and the target material 12, the same voltage is applied to all the surfaces of the cathode and the same voltage is applied to all the surfaces of the target material. However, since the lengths L1 and L2 are different, the intensity of the electric field experienced by the carbon nanotubes formed on the second horizontal surface 11c becomes relatively larger than the intensity of the electric field experienced by the carbon nanotubes formed on the first horizontal surface 11a . Therefore, electrons are emitted first from the end portion of the carbon nanotube formed on the second horizontal surface 11c, and electrons larger than the first horizontal surface 11a are continuously emitted. In the X-ray ionizer of the present invention, the deterioration of the carbon nanotubes progresses gradually due to this phenomenon, and as a result, the rate of decrease of the amount of X-ray generated as the use time is slowed down. The above effects are as follows. As the carbon nanotubes emit electrons, the ends of the carbon nanotubes are continuously deteriorated. In the deteriorated carbon nanotubes, the electron emission effect is decreased. If deterioration occurs in the same pattern on the entire surface of the cathode, a reduction in the total electron emission amount occurs in a manner that occurs in individual carbon nanotubes. However, if the electron emission is relatively large in a specific region such as the x-ray ionizer of the present invention, and the deterioration of the carbon nanotube is relatively large, the decrease in the initial electron emission amount may be large, and the slope of the decrease in the overall electron emission amount may be slowed down.

The steps of the cathodes applied to the X-ray ionizer of the present invention can be configured in various forms. The ratio of the area of the protruding area to the depressed area can be adjusted and the inclination of the step in the connecting area of the protruding area and the depressed area can be adjusted. When a step is formed on the surface of the cathode in any form, the density of carbon nanotubes causing electron emission is increased, so that the amount of electron emission is increased, or the number of carbon nanotubes for electron emission is increased. I have. Further, by controlling the inclination of the connection region between the protruding region and the recessed region, the degree of electron emission from the horizontal plane and the inclined plane can be controlled, and as a result, the deterioration tendency of the carbon nanotube over time can be controlled.

Figure 6 illustrates a cathode structure having a step that can be applied to an x-ray ionizer of the present invention. Referring to FIG. 6 (a), a cathode has a first horizontal surface, which is a depression, and a second horizontal surface, which is a protrusion, and the horizontal surfaces are connected to a vertical surface. In such a structure, the carbon nanotubes formed on the horizontal surfaces are easily arranged in the direction of the target material, but the carbon nanotubes formed on the vertical surface are difficult to be aligned in the direction of the target material. However, the above structure has an advantage that the area of the horizontal plane can be maximized. The area ratio of the first horizontal plane to the second horizontal plane is preferably in the range of 1: 2 to 2: 1. If the area of the first horizontal plane is excessively large, the initial electron emission amount is excessively small. If the area of the second horizontal plane is excessively large, the electron emission reduction slope is excessively large. Referring to FIG. 6 (B), a first horizontal plane, which is a depression, and a second horizontal plane, which is a protrusion, are formed, and the horizontal planes are connected to an inclined plane. This structure has a smaller horizontal surface area than the structure shown in FIG. 6 (a), but the carbon nanotubes on the sloped surface are easily arranged in the direction of the target material. The carbon nanotubes formed on the horizontal plane have higher electron emission efficiency than the carbon nanotubes formed on the inclined plane or the vertical plane because of a part of the geometric structure in which the carbon nanotubes are liable to be aligned in the target direction by the electric field, This is partly due to the fact that the emitted electrons are more likely to collide with other surrounding carbon nanotubes. Therefore, it is preferable that the first horizontal plane, which is the second horizontal plane on which electron emission is easiest, the arrangement of carbon nanotubes, or the inclined plane where electron emission is inhibited by collision with electrons, The optimum cathode step structure can be derived by adjusting the area and the inclination angle of the cathode. The area ratio of the first horizontal plane to the second horizontal plane is preferably in the range of 1: 2 to 2: 1. If the area of the first horizontal plane is excessively large, the initial electron emission amount is excessively small. If the area of the second horizontal plane is excessively large, the electron emission reduction slope is excessively large. The slope of the connecting surface between the first horizontal surface and the second horizontal surface is preferably in the range of 30 to 70 degrees. If the slope of the connecting surface exceeds 70 degrees, the electron emission at the slope decreases excessively. If the slope of the connecting surface is less than 30 degrees, the area of the horizontal surface becomes excessively narrow. It is preferable that the step between the first horizontal surface and the second horizontal surface is in the range of 1/10 to 1/3 times the radius of the disk-shaped cathode. If the step difference is less than 1/10 of the radius of the disk-shaped cathode, the effect due to the step difference is excessively small, and if the step radius exceeds 1/3 of the disk-shaped cathode radius, the initial electron emission amount may be excessively small.

FIG. 7 is a view for explaining whether or not the power section of the conventional X-ray ionizer of the present invention and the X-ray ionizer of the present invention are exposed to an X-ray. 7 (A) shows a conventional X-ray ionizer. In the conventional X-ray ionizer, the distance between the power unit 20 and the X-ray generator 10 is short The power unit 20 is partially exposed to the X-ray generating unit 10. Therefore, only the control section 30 is present in the electromagnetic wave shielding region 50, and the electronic elements of the power section 20 may cause malfunction due to the X-ray and the manufacturing equipment noise. 7 (b) shows an X-ray ionizer of the present invention. The power unit 20 and the control unit 30 of the X-ray ionizer are built in one electromagnetic shielding case 60, (10) is connected by a long cable (40). In this case, the X-ray generator 10 may be installed in a static elimination work space provided with a separate X-ray shielding means, and the power unit 20 and the control unit 30 may be completely present in the electromagnetic wave shielding area 50.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 (Production of Carbon Nanotube Growth Cathode Having Flat Surface)

A cathode substrate made of a stainless steel material having a diameter of 7 mm and a thickness of 2 mm and having a flat surface on which carbon nanotubes are to be grown was subjected to reduction treatment first. The reduction treatment was performed to reduce the surface of the cathode substrate while supplying 1000 sccm of an inert gas such as argon gas and 400 sccm of hydrogen gas as a reducing gas at a reaction temperature of 600 캜 for 10 minutes. Subsequently, carbon nanotubes were grown on the surface of the reduced cathode substrate. Specifically, the carbon nanotubes were directly synthesized and grown on the surface of the cathode substrate while supplying 10 sccm of acetylene gas, 1000 sccm of argon gas, and 400 sccm of hydrogen gas at 600 ° C for 10 minutes.

Example 2 (Production of carbon nanotube growth cathode having horizontal plane and vertical plane)

A stainless steel cathode substrate having a diameter of 7 mm and a thickness of 2 mm and having a horizontal plane and a vertical plane as shown in Fig. 6 (a) was first subjected to reduction treatment on the surface on which the carbon nanotubes were grown. At this time, the area ratio between the horizontal plane and the vertical plane was 1: 1. The reduction treatment was performed to reduce the surface of the cathode substrate while supplying 1000 sccm of argon gas and 400 sccm of hydrogen gas as a reducing gas at a reaction temperature of 600 캜 for 10 minutes. Subsequently, carbon nanotubes were grown on the surface of the reduced cathode substrate. Specifically, the carbon nanotubes were directly synthesized and grown on the surface of the cathode substrate while supplying 10 sccm of acetylene gas, 1000 sccm of argon gas, and 400 sccm of hydrogen gas at 600 ° C for 10 minutes.

Example 3 (Production of Carbon Nanotube Growth Cathode Having Horizontal Plane and Slope Plane)

A stainless steel cathode substrate having a diameter of 7 mm and a thickness of 2 mm and having a horizontal plane and a vertical plane as shown in Fig. 6 (a) was first subjected to reduction treatment on the surface on which the carbon nanotubes were grown. At this time, the area ratio between the horizontal plane and the vertical plane was 1: 1, the angle of the inclined plane was 45 °, and the step between the horizontal planes was one fifth of the radius of the circular cathode. The reduction treatment was performed to reduce the surface of the cathode substrate while supplying 1000 sccm of an inert gas such as argon gas and 400 sccm of hydrogen gas as a reducing gas at a reaction temperature of 600 캜 for 10 minutes. Subsequently, carbon nanotubes were grown on the surface of the reduced cathode substrate. Specifically, the carbon nanotubes were directly synthesized and grown on the surface of the cathode substrate while supplying 10 sccm of acetylene gas, 1000 sccm of argon gas, and 400 sccm of hydrogen gas at 600 ° C for 10 minutes.

Evaluation example (comparison of change in electron emission amount of cathode)

Cathodes manufactured according to the first to third embodiments were provided in a vacuum chamber, and nodes having the same area were provided at intervals of 10 mm. Subsequently, a voltage of 30 kV was applied between the cathode and the node to emit electrons from the cathode, and the change in current was measured at each cathode over time.

Table 1 below shows the amount of current change with time. In the cathode of Example 1, the initial current value was measured to be relatively high, but it was observed that the current dropped sharply after 25 days. In Example 2 and Example 3, the initial current value was smaller than in Example 1, And the current reduction ratio according to the flow was measured to be low.

1 hours 5 days 10 days 15th 20 days 25th 30 days Current (Example 1) 2020 ㎂ 1900 ㎂ 1790 ㎂ 1670 ㎂ 1540 ㎂ 1410 ㎂ 1250 ㎂ Current (Example 2) 1970 1970 1870 ㎂ 1770 ㎂ 1660 ㎂ 1560 ㎂ 1450 ㎂ 1340 ㎂ Current (Example 3) 1920 ㎂ 1840 ㎂ 1770 ㎂ 1700 ㎂ 1630 ㎂ 1570 ㎂ 1510 ㎂

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Therefore, the embodiments described in the present invention are not intended to limit the scope of the present invention but to limit the scope of the present invention. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: X-ray ionizer 10: X-ray generator
11: cathode 12: target material
13: window 14: sealing part
15: carbon nanotube 20: power part
30: control unit 40: cable
50: electromagnetic wave shielding region 60: electromagnetic wave shielding case

Claims

In an x-ray ionizer that emits an x-ray that partially ionizes the atmosphere to remove static electricity from the charged object,
An X-ray generator for generating an X-ray by collision of an electron with a target material;
A power unit for supplying power to the X-ray generator; And
And a control unit for controlling operation of the power unit,
Wherein the cathode of the X-ray generator comprises carbon nanotubes on the surface of the target material,
A step is formed on the surface of the target material,
The power unit and the control unit are housed in one electromagnetic wave shield case,
Wherein the X-ray generator and the power unit are connected by a cable so as to be installed apart from each other.

The method according to claim 1,
The carbon nanotubes are grown directly on the surface of the target material by chemical vapor deposition,
Wherein the step is formed from a repeating structure of a horizontal plane and a vertical plane or formed from a repeated structure of a horizontal plane and an inclined plane.

The method according to claim 1,
Wherein the length of the cable is between 1 and 10 m.